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Incidence of sarcoid-like reaction demonstrated on 18F-FDG PET-CT in head and neck cancer patients


Sarcoid-like reaction (SLR) is a well-known benign cause of nodal FDG-uptake in cancer patients and needs to be differentiated from active nodal metastatic disease. This study aimed to demonstrate the prevalence of sarcoid-like reaction in head and neck cancer (HNC) patients demonstrated on 18F-FDG-PET-CT.


A 6-year-period (2008-2013) retrospective analysis of 729 PET-CT scans (308 patients) of HNC was performed. Pre and post-treatment scans were compared and cases with persistent mediastinal/hilar nodal uptake despite therapeutic response elsewhere were further analysed and clinically followed up. Final diagnosis was reached by biopsy, clinical and imaging follow-up.


SLR was diagnosed in 8/308 (2.6%) HNC patients. Of which 3 had mediastinal nodal uptake only, 2 had bilateral hilar nodal uptake only and 3 had both mediastinal and hilar uptake. All the 8 patients had primary HNC and deep cervical lymphadenopathy but no distant metastases, hence misinterpretation of SLR would have upstaged as M1 (metastasis positive). 4 cases were identified on scan for restaging of suspected recurrence, and 4 were for primary tumour staging. The mean SUVmax of SLR was 6.9 (range 2.4-9.6), and the mean SLR nodal size was 1.6cm in short axis (range 0.6-2.4cm), with no significant difference compared to active nodal diseases (P=0.33 and 0.23).


SLR was seen in 2.6% of HNC patients at 18F-FDG PET-CT examinations. 18F-FDG PET-CT plays a significant role in the management of HNC, and it is important to be aware of a possibility of SLR in order to avoid false-positive interpretation of metastasis.

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Correspondence to LI Sonoda.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Sonoda, L., Lakhani, A. & Ghosh-Ray, S. Incidence of sarcoid-like reaction demonstrated on 18F-FDG PET-CT in head and neck cancer patients. cancer imaging 14 (Suppl 1), P5 (2014).

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